A Sexual Dimorphism in Three Somatic Tissues of Cattle

Abstract

The discovery in 1949 of a sexual dimorphism in interphase neural cells of cats was followed by reports of a similar dimorphism in other mammalian species and cell types. Somatic tissues of cattle, because of their high chromatin content, were purported to be unsuitable for describing the sex chromatin, although it was observed in neural cells of normal and freemartin calves. In the present studies, liver tissue samples from 16 cows, 8 bulls, and 6 steers, were fixed in modified Davidson''s solution, hydrolyzed in hydrochloric acid and stained in thionin solution. Observations were made on 100 cells from each sample. The sex chromatin was attached to the nuclear membrane and stained a metachromatic violet while the nucleolus retained the orthochromatic blue. Seventy per cent of the female cells exhibited the sex chromatin. Male tissue characteristically displayed the chromatin in less than 10% of the cells examined.